| The distribution characteristic of mercury pollution caused by gold mining and transformation rules of mercury and methylmercury were studied through collecting water and sediment samples of the river near the Jiapigou goldfield located in the upper reaches of the Songhua River. The results show that total mercury content of the upstream river water is higher than the downstream river water, in particular, the mercury content reduces with increasing distance from the mining area when the river is near gold mine. However, in the sediment, the higher total mercury content is found in the lower reaches of the river and upper stream samples show lower total mercury content. Both of the highest total mercury content and methylmercury content of water samples are detected in the jiapigou river section, which is 0.86 μg·L-1 and 4.14 ng·L-1 respectively. The highest total mercury content of sediment samples is detected in the laojinchang river section, and the highest methylmercury content of sediment samples is detected in the erdaogou river section, which is 9.00 mg·kg-1 and 4.02 μg·kg-1 respectively. The results of mercury and methylmercury assessment show that severe mercury pollution is found in 22.22% of the river water and moderate mercury pollution is found in the else river section, and methylmercury pollution is severe in whole river water based on single factor index method. It can be found that the mercury pollution in the river sediment is very serious based on the geo-accumulation pollution index method and the potential ecological risk assessment method. The pollution situation is high environmental risk and ecological risk, it should be paid high attention by people. |
